OBJECTIVES: 1) We have found a likely early intermediate in T4 DNA replication whose elongation is arrested in certain mutants. We intend to clone the genome segment from which this presumptive intermediate is made. 2) We will attempt to synchronize early T4 DNA replication and analyze T4 DNA made at different times after infection by Southern blotting. 3) Together with Dr. Kemper, we will test the effects of certain mutationally altered single-stranded binding proteins (gp 32) on the activities of a maturation nuclease (gp 49). 4) We will continue our genetic analysis of interactions of proteins acting on DNA by isolating, characterizing and mapping second site suppressors of mutations in replication genes of phage T4 and by analyzing DNA metabolism in these suppressor mutants. 5) We will test whether gene 58/61 mutants which are defective in synthesizing RNA primers, use recombinational intermediates to prime lagging strand DNA synthesis.